| 摘要 |
Method and apparatus for establishing connections in a switch-based communications network for multicast traffic. A source receives a multicast packet on an access port from a source host, determines a group address in the multicast packet, and composes and sends a "sender present" message to other switches on its network ports. The receiving switches determine whether a local host wishes to join the group and if so, send a map message back toward the source switch on a predetermined path between the receiving switch and the source switch. A map message may terminate at a switch on the path that already has a connection for this group/source pair, and join into this connection as an additional output port. In this manner, a "signal out, connect back" method is provided for establishing a connection path from the sender to multiple receivers. In addition, multicast traffic can be sent across a switch/router interface in either direction, providing for controlled multicast traffic between router-based networks and switch-based networks.
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